A US appeals court last night threw out convictions against Frank Quattrone, the former high profile Credit Suisse First Boston technology banker, saying the jury was improperly instructed on how to interpret the law.

Quattrone was sentenced to 18 months in prison in September 2004 for obstruction of justice, obstruction of an agency proceeding, and witness tampering. He remained free pending the outcome of his appeal but was barred from the securities industry.